


By His Shadow

by You_Light_The_Sky



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: Alternate Universe - Demons, Demons, Horror Elements, M/M
Language: English
Status: Completed
Published: 2016-03-14
Updated: 2016-03-14
Packaged: 2018-05-26 15:36:19
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,999
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6245461
Author URL: https://archiveofourown.org/users/You_Light_The_Sky/pseuds/You_Light_The_Sky
Summary: <blockquote class="userstuff">
              <p>When Sherlock was twenty-two, he let himself by possessed by a demon. The demon never left.</p><p>Originally posted on tumblr.</p>
            </blockquote>





	By His Shadow

**Author's Note:**

> Originally posted on tumblr here: http://youlighttheskyfanfiction.tumblr.com/post/118572028746/omgomgomgomg-youre-actually-taking-prompts-im
> 
> And I finally decided to post it as a oneshot on AO3.

The thing about demons is that they used to be angels too. What does that say about angels, if they’re as easy to corrupt as human beings?

No, Sherlock thinks as he finishes the summoning circle, if angels and demons are anything like humans than the damned must be the ones who push the rules… the ones with the _answers_ he craves. They are the ones worth demanding knowledge from.

He lets his blood drop down in rivers from his eyes and his wrists and waits as the shadows twist and turn and mold themselves into something malleable, something understandable to human eyes, before a figure steps into the circle, staring down at kneeling Sherlock.

It’s… it’s himself.

“…Impossible,” Sherlock breathes.

“Nothing is impossible, if there is proof of it before your eyes,” his doppelganger, replies with whited out eyes. Nothing but a tiny dot of dark blood-red to indicate pupils. He even speaks with the same accent, the same tells and bored monotone.

“You’re not real,” Sherlock growls. “You’re an illusion. Made of mirrors. A trick of a spell. I’ll get rid of you—”

“Don’t be stupid,” the thing drawls, his disdain grating to Sherlock’s ears. “You know the spell is valid. The evidence was there when you researched it… no, you just don’t want to admit that the greatest demons… lie… in… _yourself_ ,” the thing blows smoke against Sherlock’s face.

Sherlock hisses out at him, “Leave! I don’t want you here anymore if you can’t tell me anything useful!”

“Letting your emotions get the better of you? I expected better from my human counterpart,” it drawls. “You aren’t like the other humans. You’re better than this. Accept the evidence. Move on. Remember the rules. Don’t make me repeat them, I hate repeating myself.”

 _You’re me_. Sherlock wants to snap, but he doesn’t because he hates stating the obvious. It’s human. It’s ordinary. And it’s not Sherlock. That _thing_ isn’t him either. Just a twisted version of him. A trick. He has to watch his words. He can’t let it take the advantage in this deal.

“I summoned you and now you owe me a boon… and then I pay the price for it. One way trip,” he grits out. But he’s come prepared. He has holy water tucked in his belt and protection spells against his skin. The demon won’t take him.

It nods.

“Your wish?”

Sherlock scowls. Wish. What a silly word for such a _thing_ to use.

“You know what I want.”

Its lips widen, showing the faint glimmer of opal teeth. “To numb one’s emotions requires an… inhuman transformation. You could say it’s not possible.”

“I don’t care,” Sherlock snaps. “Make it stop. I don’t care what I have to do. This… this _feeling_ is a weakness. Let me transform.”

“You would have to give up the silly factors that make you human… surrender yourself to the inhuman within yourself.”

“Do it,” Sherlock regrets saying. How silly, in the end, Sherlock Holmes falling to such emotions. Mycroft would laugh if he knew, bloody robot.

It’s eye flash red and lips widen to a complete black smile and before Sherlock can change his mind, the being engulfs him in shadow and he feels—

Nothing. A man with eyes that flicker into pure white with red dots, stands instead, and chuckles softly into the night.

-

When Sherlock was twenty-two, his parents died.

When Sherlock was twenty-two he sold his emotions away.

When Sherlock was twenty-two, he let a demon possess him and he… well, he became it, didn’t he?

-

“Who would want a flatmate like me?” John half feels like chucking his barely-sipped coffee into a bin.

Mike hesitates.

“Well, it’s not like you’re Sherlock.”

John blinks.

“Sorry, who?”

“Sherlock Holmes,” Mike shakes his head and even shivers, “one of the coldest blokes you will ever meet. Never met anyone who… well, I guess you’ll see if you ever meet him. But I heard he lives alone. Dunno how he affords it, you’d think he’d be living somewhere more… gritty… with what he gets paid. Which is practically nothing. Must live off of some family funds or something.”

“Huh,” John perks up, despite himself. “Is he really that bad?”

“Oh, you have no idea,” Mike groans. “Bastard would probably be on the Yard’s hit list if the Yard could do that sort of thing. You really don’t want to meet him but he’s the only one I know of who might need a flatmate and I pray for the sorry sod who has to put up with him.”

“Well then…” John looks at Mike and Mike must recognize this particular look because suddenly he’s chuckling (finally) and shaking his head.

“Now _there’s_ the John Watson I know. Not so gone after all. Alright then, you suicidal git,” Mike pats him fondly on the back, “I’ll introduce you two. But I reserve the right to say ‘I told you so’ when it all goes to hell.”

John just shrugs, his heart pumping like it did before he rushed to war.

-

One of the more amusing (and later, _boring, predictable, how stupid_ ) traits of the human species is how much they _fear_ outsiders.

Humans may not be able to _see_ it, but some innate part of them _knows_ that Sherlock is no longer human. A single look into Sherlock’s eyes and they avoid his gaze for the rest of their short acquaintance with him. They shiver when he talks and avoid touching his hands for handshakes. They whisper when he arrives at crime scenes and even this body’s brother, Mycroft, seems disgusted with him for reasons beyond his brother’s choice in career.

They all ooze in fear.

He prefers it that way. Humans are predictable. Slow. Stupid. He can feed enough on their fear though the taste is bland. Nourishment is nourishment and what matters to him is the chase of knowledge, the glittering of a new puzzle. He can feed enough on the essence of sin from the criminals he drains to their near-deaths.

But then he meets John Watson and the delicious, exquisite taste of John’s loyalty and he has to have _more_.

-

“Who the hell is this?” people ask when they see him with Sherlock.

“My flatmate,” Sherlock always replies with disdain (perhaps, for their incredulity or what Sherlock constantly says is humanity’s stupidity), “obviously.”

And, as always, they are met with dropped jaws and startled curses of ‘who would be crazy enough to…?’ and John wishes there was a mute button one could put on other people. At least when they repeat things that one’s heard for the past four weeks.

John doesn’t understand it.

Mike has called John several times, asking if John wants to change his mind with hushed tones and letting John know that Mike is here to talk anytime John needs anything. The girl at the morgue, Molly, never looks Sherlock in the eye and later tentatively told John that her morgue was open if he ever needed a place to duck out. Donovan gave him a taser (and where the hell did she even get that) to use ‘just in case’ while Mycroft (bloody bastard) just looked as if John was a broken animal walking to his death.

He’s tried asking Mrs. Hudson and Lestrade, the two people Sherlock seems to tolerate, about it. But Mrs. Hudson just glanced up at the ceiling above, as if Sherlock could hear them upstairs, and said, “Oh it’s just nothing but a string of coincidences… there’s no actual proof…” before convincing John to join her in another Connie Prince marathon. Which he indulged. (And may secretly enjoy, shut up, Sherlock.)

Lestrade, though, was a bit more elaborate.

First he asked John to come into his office, a strained smile on his face when he saw Sherlock’s dark look as he put an arm around John (though John doesn’t know why. Sherlock’s like that with everyone. Always glaring. Except with him, which is nice. Because they’re friends, of course.)

“Are you and him…?”

John flushes. “None of your business but no. He’s not interested.” At least John doesn’t think he is. Honestly, John never thought to ask.

“Oh. Well, that’s good. Really good then—”

John really hopes Lestrade is not hitting on him because John may be bi but he’s not interested in Lestrade either—

“—just… be careful around him, yeah? He… Well, no one says anything because it sounds ridiculous but… he just…” Lestrade glances nervously at the closed door and then back at John, “Well, there are these _dreams_ , John. More like nightmares really. Worse than nightmares.”

John stares.

“You haven’t had them?”

John shakes his head.

Lestrade’s face falls but then he straightens up. “Look it’s not too late for you. Just leave. Get another flatmate. Sherlock _does things_ to the people he meets… it sounds crazy but everyone who meets him gets these… these _dreams_ and…”

“Right…” John steps away. “Well, thanks for the chat.”

Some people are just so prejudiced against others. Sherlock’s not the most touchy feeling kind of bloke but that’s how John prefers it. Sure, he doesn’t smile except at corpses and now, occasionally, at John with that lazy cat grin, but he’s a good man.

John is sure of it.

-

John Watson is an anomaly. A soldier with fine-tuned instincts for danger and yet he rushes into it and seems to blatantly ignore the natural instincts other humans have to stay away from Sherlock. _Freak. Psychopath. Demon_. Oh how close to the mark humans can be sometimes.

But not John.

John smiles at him. John calls him brilliant and doesn’t edge away when Sherlock tests him by whispering into his ear or taking his hand. John just shivers and seems to thrive on the danger that Sherlock provides, John talks back and shoots a man for him and his emotions are so _glorious_ to taste. Sherlock never knew there was a better taste than fear, never knew he didn’t have to look to puzzles for stimulation from the boredom of a bland palette.

He looks at John and he wants to cage him, observe him, taste him until he becomes bored of John’s emotions and has to taste John’s flesh instead and—

Sherlock doesn’t notice his shadow flicker behind him when he thinks of John.

( _Did you know, Other Me?_ the shadow smiles, biding his time, _Demons can Fall too. So Fall._ )

-

Sherlock starts holding John’s hand. At first, John questioned it, but Sherlock just gave him an intense look as always and said it was an experiment.

Weird way to ask for a bloke’s hand but John will take what he can get. After the Blind Banker case, John realizes he can’t walk away from his feelings. He’s in love with bloody Sherlock Holmes, the bloke that never smiles or seems to react to anything but his puzzles. If it takes an experiment for Sherlock and him to do anything like a couple, then so be it.

The reactions to said hand-holding would be hilarious if John wasn’t offended on Sherlock’s behalf. Lestrade drops his coffee. Donovan openly gapes at them and then tells John to use the taser whenever he needs it. Mrs. Hudson quirks an eyebrow, giggles and then advises John about dating the dangerous ones. Mycroft disappears with Sherlock for five minutes before Sherlock storms back and grabs John’s hand again.

That’s another thing: Sherlock never lets go of John’s hand if he can help it. Whether it’s the loo or bed, Sherlock drags John with him. John hasn’t showered in three days and decides that later he’ll just say ‘fuck it’ and tear away from Sherlock to get clean.

If John wasn’t convinced that Sherlock is asexual, he’d think that Sherlock was trying to court him in that odd way of his. His fingers are always stroking John’s palm and Sherlock fixed that intense gaze on John again, as if he wants to extract something from John that John doesn’t know about.

John still doesn’t have bad dreams, and so he doesn’t worry.

-

 _Ironic, don’t you think?_ his human shadow whispers to him when Sherlock tries to puzzle out the source of his fascination for John Watson. The obsession with John’s hands. _Our presence causes humans to have nightmares. We unsettle all who we come across… and yet when John sleeps… he has good dreams…_

“Shut up,” Sherlock mutters to it. “I don’t need your pointless commentary.”

His shadow just laughs. And waits.

-

When John gets hurt, Sherlock’s face always becomes eerily blank. In those moments, John feels like he’s on the battlefield again, heart racing as he faces another soldier. But Sherlock never does anything differently. He acts as if John’s injuries aren’t there, stalking off with that blank look, leaving John alone.

It’s a harsh reminder that John doesn’t really matter.

In those moments, John wonders if Lestrade and the others are right about Sherlock. But then he shakes himself out of his doubt. No. Of course not. Sherlock is a good man. He has to be. Why else does he help others with all these cases?

 _Because he’s bored_ , a voice like Donovan’s echoes in his ears.

John scowls.

Bored or not, Sherlock still helps. That’s better than most of humanity.

-

Someone’s touched John. Someone’s _touched. John._ He stalks off. Sinking into the shadows and creeping up behind the attacker (a mundane, stupid man named Hubert Dumas) and before he knows it, red is everywhere, spilling on the pavement and bones are crunched and _this man touched John so he will make him suffer tenfold—_

His shadow leans against the bookshelf, preening like a cat. _Just a little more_ , his shadow says. _Fall a little more…_

-

Sometimes when John wakes up, he thinks he sees Sherlock by the curtain, watching him in the dark. But then he blinks and Sherlock is gone.

The hand-holding experiment ended last night. John slowly gets up, checking on his bandages and realizes that they’ve been changed.

Unconsciously, he smiles.

-

“I know what you’re doing,” he hisses to his shadow. “I know you’re trying to make me _feel_. But I refuse. You won’t make me. I’ll stay as far away from John if I have to…!”

His shadow is shaking. But not with fear. _Are you afraid I’d take him away?_

He snarls, almost hitting the wall (how silly, to try and attack your own shadow) because no one will take John away. Not his delicious emotions. Or that intense warmth John gives out when he looks at Sherlock alone, it’s _his—_

Damn it. He has to stay away.

_-_

Sherlock ignores him the entire case. Five ticks and Sherlock doesn’t seem to think that John’s worthy enough to speak to. When John nearly takes a bullet for Sherlock (not that Sherlock would know, on that dark and flashing stage, when they confronted the assassin) and Sherlock says nothing, John stalks off.

He knows that Sherlock will never love him. Sherlock doesn’t love anyone. But he had hoped that maybe, just maybe, Sherlock cared about him and maybe even… had a use for him (not need, because no one needs John. Not anymore.)

John’s on that depressing train of thought when he gets kidnapped.

He almost wants to burst into giggles when Jim the IT guy is revealed to be Moriarty and claims that John is Sherlock’s beloved pet.

Beloved? Not even close.

John doubts Sherlock will come. No one will unless it’s for the game.

-

John is gone. He feels it in his bones. Someone’s touched what’s his. John’s emotions are bitter. Dark. Not-right, not-right, not on his doctor. But where is John. He consults his shadows, tries to search out the emotions of others but he can’t concentrate and he needs to find John needs—

 _I can take over for you,_ his shadow settles by his side.

“Shut up!” he growls. “I don’t need you!”

The shadow scoffs. _This is hardly your area of expertise._

“Like anything you know will be useful,” he spits out. He needs to find John. John, John, John, where are you, what _is this—_

His shadow bursts out laughing, louder than ever. _You still don’t know? The all-powerful demon?_

“What?!” if he could rip his own shadow from him, he would.

The shadow pauses for effect. Damn self.

_…It’s love._

The demon, Not-Sherlock and Sherlock both at once, pauses.

“No,” he thinks aloud, “not love. Obsession. Fascination.”

He can feel his shadow smiling.

“NO. No, no, no, _no_! I locked you away, I _locked you away—_ ”

 _You can’t lock yourself away, demon._ The shadow creeps up over him. _Don’t you know? Demons live in all of us._

-

Moriarty and Sherlock meet in a pool.

London falls into darkness for exactly two minutes before Sherlock walks out with an unconscious John in his arms.

His shadow is gone.

-

John wakes and Sherlock is smiling ( _smiling?)_ tenderly at him. Not that slow cat-like smile, but something of tenderness. Like John is special. Precious. Always. And John has to look away because it’s too painful to look at such warmth and intensity at once—!

“No,” Sherlock whispers gently, hands moving John back in place. “Stay.”

“S-Sherlock… are you okay…?” John feels more alarmed as Sherlock strokes his cheek and he realizes that his other arm is around John’s waist. “What happened to Moriarty? The pool? I was strapped to a bomb—!”

“Shh…” Sherlock whispers against his lips and John nearly has a heart attack right there. “Think only of me.”

He kisses him like a lover would and that’s when John pulls away.

“S-stop. What… what’s happening? Who… Who are you?!” John demands because there’s no way that Sherlock would ever be interested in him.

Dark eyes (since when have Sherlock’s eyes been dark?) glint in the shadows.

“Why… I’m the _real_ Sherlock, of course.”

He kisses John again, like a man hungry for air.

-

_Do you know how Demons Fall?_

_They Fall in love._

_(But what’s that?)_


End file.
